1. Field of the Invention
This invention relates to methods for preparing the composition containing amorphous iron oxide hydroxide, the desulfurizer comprising the same, and methods for preparing and regenerating the desulfurizer.
2. Description of the Related Art
Sulfide is produced in many industrial occasions, such as process of producing chemical raw materials from coal or oil, waste water, or gas in the industrial emissions. Wherein, there are lots of sulfur-containing substances in the raw materials. And hydrogen sulfide can be discharged from these sulfur-containing substances during the process of production, so as to result in catalyst deactivation in the subsequent production. Also, hydrogen sulfides in the waste water or gas will cause environmental pollution, or poisoning of human and animal if discharged without any treatment.
In order to effectively reduce sulfide especially to minimize the effects of sulfide on the industrial production and the environment, researchers pay enough attention to the research and development of the desulfurizer. There are lots of desulfurizer for removal of hydrogen sulfide in the existing technologies, and a traditional and important one is the iron series desulfurizer which is produced by mainly using iron oxides as the active ingredients of the desulfurizer, wherein iron oxides includes ferroferric oxide and iron oxide hydroxide (FeOOH). However, the iron series desulfurizer in the existing technologies has a shortcoming that sulfur capacity is not high enough. In addition, the used desulfurizer in the existing technologies (including iron series desulfurizer) cannot be regenerated or is difficult to be regenerated, so that lots of waste agents have to be landfilled, and this may cause waste of reusable resources in used desulfurizer and environmental pollution.
Because of the good desulphurization property, iron oxide hydroxide is widely used as desulfurizer in chemical field. In addition, the preparation method for amorphous iron oxide hydroxide is a laboratory method, which needs to be protected with nitrogen and the method is relatively complicated.
In the existing technology, especially in the industrial application, there is very few desulfurizer of amorphous iron oxide hydroxide used. Even if there exists the desulfurizer of amorphous iron oxide hydroxide in the market, the content of amorphous iron oxide hydroxide is low (less than 40%), and the content of iron oxides which cannot be regenerated is high, such as ferroferric oxide, ferric oxide or iron oxide hydroxide in other crystalline state. This causes poor desulfurization property of amorphous iron oxide desulfurizer, and further causes the desulfurizer not to be regenerable, or no use value even if it can be regenerated.
The final objectives of this study are to achieve the mass production of amorphous iron oxide hydroxide with high purity and sulfur capacity, and even regeneration of used amorphous iron oxide hydroxide in industrial production. If these two objectives can be achieved, it will be a significant revolution in the desulfurizer field and the two following shortcomings of the existing desulfurizer can be eliminated. (1) Because the preparation of iron oxide hydroxide is closely related to the reaction conditions such as pH value, temperature, and oxide, iron oxides (such as ferroferric oxide, ferric oxide) or iron oxide hydroxide in different crystalline states can be obtained through different preparation methods. The content of amorphous iron oxide hydroxide in the product is low (lower than 40%) so the product has low sulfur capacity and cannot be regenerated; (2) In the existing technology, the other kinds of desulfurizers cannot be regenerated or the regeneration cost is very high, so lots of waste agent has to be landfilled, and this may cause waste of reusable resources in used desulfurizer and environmental pollution.